Fasteners with conforming sleeves

Abstract

A sleeve interference fastener including a conformable sleeve, wherein the conformable sleeve is comprised of at least one first material having a hardness of X, and a pin member, wherein the pin member is comprised of at least one second material having a hardness of Y, wherein X is sufficiently less than Y so that, in an installed position of an interference fit, at least a portion of the at least one first material of the conformable sleeve conforms to a contour of an inner surface of a hole of a composite structure so as to create a continuous electrical contact at an interface between the inner surface of the hole of the composite structure and the conformable sleeve.

We claim: 
     
       1. A sleeve interference fastener, comprising:
 a conformable sleeve having
 a tubular portion-including an inner base layer, 
 an inner diameter and an outer diameter, wherein the outer diameter of the tubular portion is less than an inner diameter of a hole of a structure, and 
 wherein the inner base layer is comprised of at least one first material having a hardness of X and a malleability of S; 
 
 an outer coating layer,
 wherein the outer coating layer is located on the outer diameter of the tubular portion of the conformable sleeve, 
 wherein the outer coating layer is comprised of at least one second material having a hardness of Y and a malleability of T; 
 
 a pin member including a shank portion having a diameter greater than the inner diameter of the tubular portion of the conformable sleeve, and wherein the pin member is comprised of at least one third material having a hardness of Z; 
 wherein, based on i) Y being equal to or less than 100 HRB on Rockwell B scale, ii) Y being less than X, iii) Z being equal to or higher than X, and iv) S being less than T, the conformable sleeve is configured so that at least a portion of the outer coating layer can fill voids being present within an inner surface of the hole of the structure to result in an interference fit formed between the conformable sleeve and the inner surface of the hole of the structure. 
 
     
     
       2. The sleeve interference fastener of  claim 1 , wherein the outer coating layer is a fixed solid coating. 
     
     
       3. The sleeve interference fastener of  claim 2 , wherein the fixed solid coating comprises: i) at least one organic material and ii) at least one conductive filler material. 
     
     
       4. The sleeve interference fastener of  claim 2 , wherein the fixed solid coating comprises a metal material. 
     
     
       5. The sleeve interference fastener of  claim 4 , wherein the metal material comprises one or more metal elements selected from a group consisting of silver, aluminum, gold, and nickel. 
     
     
       6. The sleeve interference fastener of  claim 1 , wherein, to facilitate a movement of the pin member through the conformable sleeve, the fastener further comprises a lubricant. 
     
     
       7. The sleeve interference fastener of  claim 6 , wherein the lubricant comprises a conductive solid film material. 
     
     
       8. The sleeve interference fastener of  claim 7 , wherein the conductive solid film material comprises carbon nano-tubes at a concentration between 0.05 to 30 percent of a total weight of the conductive solid film material. 
     
     
       9. The sleeve interference fastener of  claim 1 , wherein a thickness of the outer coating layer varies in a range of 3 to 25 microns.